42.6.2.6 QDEC Operation Mode

In QDEC mode of operation, Signal 0 and Signal 1 control logic inputs refer to Phase A and Phase B in X4 mode, and to count/direction in X2 mode. The Signal 2 control logic input refers to the Index, in both X4 and X2 mode of operation. In X4 mode, a simultaneous transition on Phase A and Phase B will cause a QDEC error detection (STATUS.QERR).